It appears that in some circumstances, the link that is sent when you change your email for the forum can contain a "-" as the last character, which breaks auto-linking in some email clients. You might want to wrap the link in an anchor tag or something. This messed me up several times before I noticed it.

Thanks, we'll take a look.

Which email client(s) in particular? Would wrapping the URL with < > be sufficient?

It was Postbox. I didn't check anywhere else. Not sure if wrapping would work though I think it might.